SCIENCE · INVESTIGATE AND EXPLAIN

Stress-test an energy recommendation

Separate immediate service, stored reserve and future uncertainty.

Learning outcome: Defend a bounded decision using a matched comparison and changed-condition ledger.

Starting recap

Stress cards are paper cases distinct from the twelve selectable recipes.

All lessons are open directly. Your saved experiments remain when you leave and return.

Try

Reduced middle generation 0,4,4,0 has no charging surplus: 8 local + 2 grid serves 10 of 16 kWh.

Open the experiment

Predict

Can a larger empty store solve a deficit without any charging opportunity?

Your prediction and reason

Experiment

Capture ideal fast versus slow at middle generation, then solve reduced-generation and increased-demand stresses.

Match generation timing, storage and electrical service

Original four-hour electrical service scenario · separate lifecycle evidence · Original four-hour scenario: four one-hour bins each request 4 kW. All generation packets offer 16 kWh; initial storage is zero. Local supply, surplus charging, deficit discharge and at most 1 kW grid support follow a fixed greedy rule. Curtailed potential is not generated bus input. No forecast, emissions, prices, degradation or reliability certification is calculated.

Available local generation timing: Middle-period availability Storage capacity, power and efficiency profile: Ideal fast storage

Reset keeps your prediction, captures and practice history.

Same requested service, different timing and limits

Middle-period availability; Ideal fast storage. Every case requests 4 kW for four one-hour bins: 16 kWh over a four-hour window, not a whole day. Available local generation also totals 16 kWh. Initial storage is zero. Predict whether equal totals are sufficient before comparing the timing and storage controls.

Storage capacity is 4 kWh internal energy. Charge input power is limited to 4 kW; useful discharge output is limited to 4 kW. Charge efficiency is 100% and discharge efficiency is 100%. These are supplied reference profiles, not measured device ratings.

Grid import follows storage discharge and cannot exceed 1 kW. There is no grid charging or grid export. Surplus and deficit cannot coexist in a bin, so charging and discharge never occur together. This stipulated greedy rule is not scheduling optimization. Curtailed potential is unused availability, not generated energy dissipated inside the bus.

Close two distinct accounts

Physical account (kWh): 12 used local generation + 1 grid + 0 initial store = 13 served + 0 charge loss + 0 discharge loss + 0 final store. Residual: 0.

Availability allocation (kWh): 16 available generation + 1 grid + 0 initial store = 13 served + 4 curtailed potential + 0 conversion losses + 0 final store. Residual: 0. This second account allocates potential generation; it does not imply all availability entered the physical bus.

Served 13 + unserved 3 = 16 kWh requested. Do not add unserved demand to either energy balance, or count battery output a second time as a new primary source.

Each bin lasts 1 h. Energy columns are kWh; the first two numerical columns are kW.
Bin	Demand kW	Available kW	Demand kWh	Available kWh	Direct	Charge input	Used generation	Curtailed potential	Storage output	Grid	Served	Unserved
1	4	0	4	0	0	0	0	0	0	1	1	3
2	4	8	4	8	4	4	8	0	0	0	4	0
3	4	8	4	8	4	0	4	4	0	0	4	0
4	4	0	4	0	0	0	0	0	4	0	4	0

Internal storage and energy accounts, all in kWh; start + stored charge − internal withdrawal = end.
Bin	Start store	Stored charge	Internal withdrawal	End store
1	0	0	0	0
2	0	4	0	4
3	4	0	0	4
4	4	0	4	0

Reserve and service are different indicators

The illustrative end-reserve target is 1 kWh internal energy. Final store: 0 kWh; reserve shortfall: 1 kWh; target not met. This comparison did not constrain dispatch and does not guarantee future service. It is not another course requirement. Stored internal energy is not identical to deliverable energy for the lossy profile.

The 75% discharge case assigns all modeled loss to discharge for clarity: 4 kWh withdrawn delivers 3 kWh and loses 1 kWh to conversion. It is not a measured battery rating. No self-discharge, aging, thermal constraints, within-bin fluctuations, costs or emissions are calculated.

Check timing, capacity and an unfamiliar duration

Middle-period availability with ideal fast storage ends each bin at [0,4,4,0] kWh. The first bin still has 3 kWh unmet demand: later generation cannot serve an earlier request. With ideal slow storage the stores are [0,1,2,1]; 5 kWh remains unserved across the window despite meeting the final reserve target.

For a separate paper case, an ideal full 4 kWh store limited to 1 kW output can deliver at most 0.5 kWh in half an hour. Multiply power by duration; the numerical equality of kW and kWh in the live one-hour bins is a convenience, not a unit identity.

Served 13 of 16 kWh requested; unserved 3 kWh; final internal store 0 kWh.

Physical account: 12 used local generation + 1 grid = 13 served + 0 losses + 0 final store (kWh). Curtailed available potential 4 kWh is separate. Illustrative reserve shortfall 1 kWh; this does not establish future service.

Observation to attach to a capture

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

Test a recommendation against a different condition

A favorable result in one schedule is not proof of reliability under every condition. Start by choosing a baseline generation and storage profile. Record requested service, initial store, grid-support cap and the dispatch order. Then predict how one changed input could expose a weakness before working through the stress cards.

The selectable cases always request 16 kWh over four hours and make 16 kWh local generation available. The stress cases below deliberately change those totals on paper. They do not add hidden controls or alter a saved recipe. Label your paper results separately from captures of selectable cases.

Reduce available generation while retaining demand

Replace the middle-period packet [0,8,8,0] kW with [0,4,4,0]. Demand stays 4 kW each hour, initial storage stays zero and the grid cap remains 1 kW. Predict whether a larger storage capacity could fix both deficit intervals.

No bin has surplus energy to charge any storage profile. The middle bins supply 8 kWh directly. Grid support supplies 1 in each outer bin, totaling 2. Served demand is therefore 10 and unserved demand is 6 kWh for every profile. Ending storage, losses and curtailed potential are all zero.

Check the physical account: 8 used local + 2 grid = 10 served. The request account is 16 requested = 10 served + 6 unserved. A larger initially empty store cannot manufacture missing energy; its usefulness depends on charge opportunities as well as its size.

Increase requested service at unchanged generation

For another paper stress, retain steady generation [4,4,4,4] kW but raise demand to 6 kW in every bin. Starting empty, no profile can charge because local generation never exceeds demand. Each bin supplies 4 local plus 1 grid and leaves 1 kWh unserved.

Over the window, requested service is 24, served is 20 and unserved is 4 kWh. Used local generation totals 16 and grid import totals 4. Unlike the first stress, this comparison changed requested service. Do not describe it as an equal-demand efficiency test or compare percentages without naming their denominators.

Compare reserve with immediate delivery

Return to the selectable middle-period packet and ideal slow storage. It serves 11 kWh, leaves 5 unserved and finishes with 1 internal kWh. That meets the separate illustrative reserve objective while failing some present demand. Capture this result and compare ideal fast storage: 13 served, 3 unserved and zero final store.

The reserve target does not constrain dispatch and does not guarantee future service. A power-limited store can retain energy that it could not deliver fast enough; a lossy store cannot turn every internal kWh into one delivered kWh. State which objective your recommendation prioritizes rather than declaring either case universally successful.

Electricity-storage context from EPA supports examining timing and environmental consequences. It does not transform this four-hour model into grid reliability certification. The lab omits degradation, within-bin fluctuations, forecasts, tariffs and operational optimization.

Assemble a bounded decision brief

Retain your initial prediction, two matched captures, one intermediate energy ledger and a clearly labeled paper stress. Name an improved and a worsened indicator, an alternative strategy and a measurement that could change your recommendation. More generation, changed service timing or different support are possibilities to investigate, not outcomes calculated by extra hidden model controls.

The brief contributes evidence toward later environmental review. Correct arithmetic and a saved capture do not independently establish decision quality. A reviewer needs the assumptions, functional service and uncertainty as well as the final numbers.

Transfer: identify what remains unknown

A fictional plan serves all 12 kWh requested over three hours but ends with zero storage. Another serves 11 and ends with 2 internal kWh. Can the numbers alone select the better plan or establish tomorrow’s reliability?

Check the energy-stress transfer

The first meets the immediate request; the second leaves 1 kWh unserved but retains internal energy. Priorities, future demand, charging opportunities, power limits and efficiency remain unspecified. Neither a reserve nor an immediate service total alone establishes future reliability or a universally preferred choice.

Apply

Public practice checks a specific claim. It does not establish independent mastery.

Identify a worsened indicator, an alternative and evidence that would revise the recommendation.

Your explanation and limitations

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Previous: Compare lifecycle burdens at matched service Next: Define transport service before comparing vehicles

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